Variable condenser



March 8, 1938. A, SCHMIDT 2,110,179

VARIABLE CONDENSER Filed Oct. 50, 1933 Sheets-Sheet 1 v i ll mmm myzzwzzzzzw/ I w ATTORNEY 2 Sheets-Sheet 2 are VENTOR ARTS (ll? 1567/41/07- ATTORNEY March 8, 1938. A. SCHMIDT VARIABLE CONDENSER Filed Oct. 50, 1935 ll Ivy; gag,

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Patented Mar. 8, 1938 UNITED STATES VARIABLE CONDENSER Arthur Schmidt, Berlin, Germany, 88118 61, to

Telefunken Gesellscha'ft fiir Drahtlose Telegraphic m. b. 11., Berlin, Germany Application October- 30, 1933, SerialNo. 695,773 In Germany October 31, 1932 2 Claims.

An object of the present invention is to provide a variable condenser which may be easily and cheaply manufactured, preferably from a ceramic material.

A further object of the invention is to provide a condenser of ceramic material in which both rotor and stator elements are formed of such material and carry condenser plates formed of thin layers of metal sprayed or galvanized thereon.

A still further object is to provide a condenser structure in which the. stator and rotor conducting elements consist of concentrically arranged substantially semi-cylindrical surfaces. Other objects of the invention will become apparent to those skilled in the art as the description thereof proceeds. v

I The novel features which I believe to be characteristic of the invention are set forth in particularity in the appended claims, the invention itself, however, as to'both its organization and method of operation will best be understood by reference to the following description taken in connection with the accompanying drawings in which;

Fig. l,is a cross section taken through theaxis of the rotor; r

Fig. la is a side view of the condenser from the right of Fig. 1 with one end broken off;

Fig. 2 is an axial section through the rotor y;

Fig. 3 is an axial cross section of the stator on y;

Fig. 3a is a side view from the left of the stator with one end broken oil; and, a

Fig. 4 is a schematic arrangement of the metallic layers of one form of the condenser.

In accordance with my invention, the rotor and'stator elements are composed of a suitable ceramic materialhaving low dielectric losses and a small thermal coefiicient of expansion. -They can be produced in a well known manner by a casting or pressing process. The ceramic material may preferably consist of a mixture of soapstone, porcelain earth and other additional substances and which is a native material known in the art under the name steatite. Due to the ceramic material being substantially .inelastic, or free from elasticity, condensers produced there-' from have the further advantage over those made of metal that practically no oscillations of the component parts at low or audio:frequencies, and

which may periodically affect the capacity, are

developed.

In the embodiment shown, the stator member (1 consists of a cylindrical wall 111 the left end iii of which is open and the opposite end consist of a closed rectangular bottom or base member a: having an integral conical extension as which is interiorly' ground to form a bearing for a conically enlarged end 9 of rotor shaft 0 which 5 may be rotated by a knob or other known means (not shown). As shown in Fig. 3, the stator has an integrally formed projecting boss I at each corner thereof to which may be secured by screws Ii an elastic metallic plate e which not 10 only reinforces and strengthens the stator but also serves as a supporting means therefor and as an electrical shield to shield the condenser from electrical disturbances in front of the panel. The plate a may be secured to a supporting spider c by any known means such as the screws 1' which enter tapped holes in the insulating member 0,

as shown. The spider c as shown has four radially extending arms i2 each having an aperture i3 through which any suitable securing means such as screws may be passed to secure the entire assemblage to the rear surface of a mounting panel or the like (not shown). The rotor element 1) consists of a substantially cylindrical portion ll connected to a central, tapered portion II by a radially extending portion it, the entire rotor element being formed of a single mass of ceramic material. The rotor is shown secured to the conical portion 9 by means of a nut q screwed onto the threaded end of p, a ring or washer 71. being interposed therebetween. The condenser plates m1 .and m are formed by spraying finely divided metal onto substantially half or 180 degrees of the outer and inner surfaces of the rotor b and stator a until thin continuous layers are formed.

Or the condenser plates may be formed by galvanizing the metal onto the surface of the rotor and stator elements in a manner known to those skilled in the art of the deposition of metals. If only about 180 degrees of the opposing wall surfaces of rotor and stator are covered or coated with metal, the available surfaces are not fully utilized. To provide a condenser of substantially twice the capacity, two separated layers each of about 1'70 to 175 degrees extent may be applied to the surfaces of rotor and stator elements as shown in Figs. 3 and 4. It is then necessary that the one layer for instance m of the rotor be continuously conductively connected to one layer, such as m1, of the stator and also layer m of the rotor should be similarly connected to layer m: of

and bearing near their outer ends on metallic I6 segmental members 21 and is supported by the stator and connected to the layers m1 and mg the members l1, l2 and mi and ma having substantially the same angular extent, as shown in Fig. 3a. The inner ends of the brushes K1 and K: may be connected to layers m and n: by the rivets it having heads ill in contact with the layers. Members Z1 and 23 may also serve as the terminals for the condenser.

Having described my invention, what I claim and desire to secure by Letters Patent is:

l. A variable condenser comprising a rectangular shaped member having a hollow cylindrical shaped extension, a spider member having a plurality of extending arms and a central hub portion, a metallic plate secured to said hub portion and to said rectangular shaped member, a metallic coating secured to the inner surface of said extension, a rotor shaft journaled in said hub portion, an elongated member formed of insulation material secured to said rotor shaft and having an exterior cylindrical surface and a me arrears tallic coating secured to said last named surface and adapted to lie closely adjacent to and 013130 site said first named coating at a predetermined angular position of said rotor shaft.

2. A variable condenser comprising in comlaination, a central stationary member, a thin, from ible metallic plate secured to said member and extending outwardly therefrom, a stator element composed of insulating material and formed into a hollow cylindrical drum, screw means securing said stator element to the outer portion of said plate, a thin layer of metal coated over the inner surface of said drum .over an area slightly less than 180 degrees, a rotor element composed insulating material and mounted within said stator element and having its exterior surface of cylindrical form, a thin layer of metal coated over the exterior surface of said element over an area of slightly less than 180 degrees, a shaft passing through said rotor and stator elements and means 20 securing said rotor element to said shaft.

ARTHUR SCHMIUIL 

